This invention relates to a densimeter and more specifically to a densimeter that can be mounted on a pipeline or other conduit carrying a fluid stream for measuring the density of the fluid.
A typical densimeter consists of a U-shaped vibrating tube having two ends and a driving force unit. The drive force unit maintains the tube's natural vibration through an electrical feedback driving circuit and supplies an output signal of the same frequency as the tube vibration. This response frequency is inversely related to the fluid's density. Thus, the density of the fluid can be calculated based on this response frequency. A temperature sensor, preferably a resistance temperature detector (an RTD sensor), is attached directly to one of the tube's end. The sensor supplies temperature information for making corrections to the measurements. The vibrating tube is calibrated for density, temperature and pressure and specific coefficients are developed which need to be used for the purpose of calculating the density of the fluid.
The U-shaped tube is housed in a casing. Two elbow shaped tubes extends from each end of the tube and extend beyond the casing. The measure of the fluid flow through the pipeline is "broken," i.e., divided into two sections. The first elbow of the densimeter is connected to the upstream section while the other elbow is connected to the downstream section of the pipeline. Thus, fluid from the upstream end of the pipeline flows through the densimeter and into the downstream section of the pipeline. The disadvantage with this type of densimeter is that it requires that the pipeline be broken, i.e., it is designed for in-line installation.
As such, there is a requirement of a densimeter that can be mounted on a pipeline without the need for breaking the pipeline.